From 2012 to 2015, the Vlassenbroek polder in Dendermonde was set up as a 240-hectare flood plain. Envisan, the environmental subsidiary of Jan De Nul Group, was responsible for the construction of 800 metres of new ring dyke. As raw material they used dredged material from the Zeeschelde between Melle and Gentbrugge. Additives were added to obtain the necessary strength and impermeability. An ingenious system, based on concrete pumps transported the sediments over water and the site. The additives were added on site before the mortar was poured into the dyke profile.
At the same time, Envisan set up a comprehensive test campaign: in the lab, the effect of 20 potential additives in different concentrations was examined. Envisan used a selection of these additives to carry out pilot studies as well. This resulted in a final design, which was then verified by an independent design agency.
Jan De Nul Group expects to be able to apply this innovative technique even further in the future, both at home and abroad.
